New construction put in place during August 2001 was estimated at a seasonally adjusted annual rate of $845.5 billion according to the U.S. Commerce Department's Census Bureau. Additionally, expenditures for improvements and repairs of residential properties in the first quarter of 2001 were at a seasonally adjusted annual rate of $169.3 billion. The cost of building materials is a significant portion of the total cost of new construction and home improvement. Consequently, building material manufacturers are continuously searching for new methods of improving their products and reducing their costs to gain a larger portion of this enormous market for building materials.
Door manufacturers, for example, have developed many manufacturing processes to improve their doors for the consumer. Innovative manufacturing techniques to produce hollow core doors reduce the expense of the door as compared to a solid door while maintaining functional features such as noise reduction and structural integrity. Alternative door materials such as medium density fiberboard (MDF) and particleboard may also reduce the cost of the door while maintaining functional features. Building doors with alternative materials or by innovative techniques, however, may result in an unfinished door that lacks the aesthetic qualities of an unfinished wood door, which are important for appealing to the consumer.
Many manufacturers apply a primer or finish coating to the door to appeal to the consumer. Primed or finished doors save the consumer time and effort and also have a more attractive appearance to some builders and consumers. Primer and paint coatings may be applied to the doors in an automated fabrication process. These coatings, however, typically require specialized equipment such as paint sprayers, separate paint booths, ventilation equipment, and driers to apply an attractive or useful coating to the doors. This specialized equipment consequently increases the cost of the finished door. Priming and painting also produces a variable finish quality according to the amount of material sprayed onto the door. Overspray may result in drips and wasted primer and paint while color variations may result from using an inadequate volume of primer and paint. Additionally, primers and paints typically contain volatile organic compounds (VOC's) that are vented to the environment. Permits to vent the VOC's and customer perception of the environmental impact of manufacturing processes may also increase the cost or consumer acceptance of the door.
Powder coating has been used as an alternative to priming and painting many metallic surfaces of building materials and components such as mailboxes, water heaters, window frames, and HVAC equipment, for example. The unique application characteristics of powder coatings provide superior consistency and uniformity of finish without drips, runs, or bubbles. Powder coating provides tough, durable films, enhancing the quality appearance of building materials. In general, performance properties such as impact resistance, flexibility, and corrosion resistance, of powder coatings are better than liquid paints. Powder coated building materials resist cracking, peeling, and marring during handling and normal service use.
Powder coating frequently costs less than priming and painting a product. Production costs are conserved through energy savings, labor costs, rework costs, reduced material usage, reduced waste disposal costs, and an increase in overall line efficiency. One advantage to manufacturers and consumers is that powder coated building materials have a superior quality finish at a reasonable cost.
Powder coating building materials is also more environmentally sound than painting. Environmental issues are a significant interest to the government and consumers. Unlike many primers and paints, powder coatings comply with environmental regulations. Primers and paints often contain VOC's, which can contribute to air pollution and, in some cases, ozone depletion. Powder coatings contain minimum amounts of VOC's and, therefore, may be perceived by the consumer to be environmentally friendly. Wet painting processes may also generate sludge, which must be disposed in hazardous waste landfills. This disposal increases the cost of the building products. Properly formulated powder coatings generate no hazardous waste. Unused or excess powder may be reclaimed and recycled, which also reduces overall product cost.
It would, therefore, be desirable to have an improved method of finishing passage doors that does not produce an unsightly finish. It would also be desirable to have an improved method of finishing passage doors that is not as costly as conventional finishing methods. Further, it would be desirable to have an improved method of finishing passage doors that is not detrimental to the environment.